In the phrase "The House has (a) big garden," what is the part of speech of the word in parentheses?

In the phrase "The House has (a) big garden," the word in parentheses functions as an indefinite article. It is used to introduce a noun that is not specifically identified, suggesting that there could be many gardens, but it refers to one of them in a general sense. Indefinite articles, such as “a” or “an,” are applied when mentioning something for the first time or when the specific identity is not crucial to the understanding of the sentence.

In this context, "a" indicates that there is one big garden, but it does not specify which garden, which is a key feature of using an indefinite article. This contrasts with definite articles like “the,” which would imply a specific garden known to the speaker and listener.

The other options don't fit because the word "a" does not describe a noun (which would classify it as an adjective), nor is it a noun on its own. Therefore, the classification of "a" as an indefinite article accurately reflects its role in the sentence.